Information processing systems with shared memory, including processors grouped in nodes associated with one another by links, are known. One of the main problems of systems of this type is the nonlinearity in performance of the information processing system as a function of the number of processors. The number of messages exchanged between the processors and the various parts of the memory in fact increases more rapidly than the number of processors, the more the sharing of the memory among the various processors requires the use of coherence messages, whose number increases very rapidly when the number of processors is increased. Certainly, increasing the number of links to enable a higher overall message rate has been contemplated. Nevertheless, increasing the number of links very rapidly increases the cost of the system and also increases the complexity of the coherence protocols in order to prevent two contradictory messages from circulating on two separate links simultaneously.